EPRI Research for Long Term Operations Technical Basis for SLR

EPRI Research for
Long Term Operations
Technical Basis for SLR
Sherry Bernhoft
EPRI Program Manager
US NRC Regulatory Information
Conference
March 2016
© 2016 Electric Power Research Institute, Inc. All rights reserved.
EPRI Long Term Operations Program
 Leverages existing research
Living research programs technical reports are updated
based on:
 Systematic approach to identify
research needs
Research
 International coordination and
collaboration
Provides the technical basis
informing decisions related to
safe, reliable and economic
long term operations
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Operating
Experience
Inspection
Results
© 2016 Electric Power Research Institute, Inc. All rights reserved.
Research Results in Use For Aging Management
Cable condition
monitoring
Reactor vessel
surveillance monitoring
Reactor internals
inspections
Over 125 EPRI technical reports are referenced
in US NRC and IAEA guidance reports.
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Concrete irradiation
impacts
© 2016 Electric Power Research Institute, Inc. All rights reserved.
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Reactor Vessel Surveillance Monitoring
 Issue: Monitor fracture toughness of the RPV
and nozzles due to irradiation and other
potential degradation mechanisms
 BWR Integrated Surveillance Program (ISP)
– Extend program out to 80 years - 2017
– Submit for NRC review - 2018
 PWR surveillance programs – will substantially
increase the data points for > 60 years
– Coordinated RV Surveillance Program
– PWR Supplemental Surveillance Program
Data and trend correlations exist for LTO. Additional data will
expand and improve existing trend correlations.
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
PWR Internals Inspection & Evaluation Guidelines
 PWR Internals Inspection and Evaluation Guidelines
(MRP-227, Revision 0) published Dec. 2008
– Currently MRP-227-A
– MRP-227, R1 published Nov. 2015
 Aging Management Strategy
– Identification of components based on relevant
aging mechanisms
– Inspect early in Period of Extended Operations
(PEO) and every 10 years thereafter
– Component selection may be revised for SLR
– MRP-227 is a living program and updated based
on research, OE and inspection results
 MRP-227 aging management strategy is robust and
will be validated for the SLR period
– MRP-227, R 2 - 2020
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Summary of To Date PWR Internals Inspections
 15 reactors inspected, others partly complete
 Initial full inspections have not identified any major
issues
 Issues of greatest concern not seen
 Observations to date:
– Almost no observed austenitic SS stress corrosion
cracking
– Irradiation Assisted SCC is extremely limited
 Currently limited to bolts
– No macroscopic effects of void swelling
 No distortions, cracking, or excessive bolting
failure
– High-strength nickel alloy clevis insert bolting
failures
 However, not in safety function load path
– Guide card wear monitoring – guidance was
updated based on OE
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
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Aging Management for Electrical Cables
 Issue: Aging of cable insulation materials due
to radiation, temperature and submergence
 EPRI Technical Reports:
 License Renewal Electrical Handbook
 Cable Aging Reports
Low voltage thermal/radiation
Low and Medium voltage
wet/submerged failure mechanisms
 Medium and Low Voltage Aging
Management Implementation Guidelines
 Cable Testing Guidelines
 In-containment Radiation and
Temperature Measurements
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Electrical cable systems are performing well
and tools exists for aging management.
© 2016 Electric Power Research Institute, Inc. All rights reserved.
Condition Monitoring: Tan δ Testing Shielded Medium
Voltage Cable
 Tan δ testing is used to evaluate shielded medium
voltage cable
 Applying EPRI Tan δ acceptance criteria will identify
degraded cable insulation due to water treeing or
thermal damage in MV cables, cable terminations and
splices
 EPRI has been collecting member test data since 2009
to evaluate effectiveness
 Report 1025262-June 2012 validated assessment
criteria
 Report 3002005321-September 2015
– Degraded cables, wet and dry, identified by tan δ
– Failure mechanism confirmation of tan δ results of
cables that tested in severely degraded criteria
– No failures of cables with good or slightly degraded
tan δ
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Electrical Cables Ongoing
 Ongoing Projects:
Continued collection of in-containment radiation and
temperature data
Enhanced condition monitoring technology
Low voltage cable susceptibility to wet (submerged)
environments
Cable materials handbook
Forensic analysis of harvested cables
Service aged cables for determination of remaining
qualified life
• Cable harvesting guidelines
• Testing of field returned (harvested) cables
• Determine Remaining Useful Life
Remaining useful life will inform need for
possible cable replacements for SLR.
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
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Aging Management for Concrete Structures
 Issue: Monitoring and aging management of
concrete structures due to radiation and
environmental exposure
 EPRI Technical Reports:
 Nuclear Concrete Structures Aging Reference Manual
 Nondestructive Evaluation Inspection of Concrete
Structures
 Literature Survey of Effects of Radiation on Concrete
 Expected Conditions of Reactor Cavity Concrete at 80
Years of Radiation Exposure
 Boric Acid Attack of Concrete and Rebar in PWR Spent
Fuel Pools
 Nonlinear Ultrasound to Evaluate Integrity of Aged
Concrete
 Pilot Plant Augmented Containment Inspection Results
 Alkali Silica Risks Ranking and Mapping
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Recent International Irradiation Data Compiled by ORNL
Data supplied
by ORNL
No appreciable impacts on biological shield wall concrete for LTO.
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Engineering Structural Evaluation:
Supports designs – PWR type 1/2/3/4
Type 1 – Shoe on Bio Shield
Support of interest
Type 2 – Metal Frame
Type 3 – Shoe on Bio Shield
Not in Scope
Not in Scope
Bio shield not structural
Used only on W 4-loop units
- 11 units are in scope for this study (2
or 3-loop, Type 1 supports)
- Documentation of the choice of Type
1 will be included in the 2016 report.
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Type 4 – Shoe on Shield Tank
Not in scope
Neutron shield tank – low fluence
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Engineering Structural Evaluation
 Finite element analysis of the
type 1 support design
– Detailed drawings from a 2-loop
and 3-loop PWR
– Modeling the reduction in margin
due to neutron irradiation:
 Swelling of aggregates/concrete
 Change in mechanical
properties
– Results of the analysis will be
published as an EPRI Technical
Report in Q4, 2016.
Finite element modeling mesh
of Type 1 RPV support
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
R&D Continuing Advances to Support Aging Management
Develop NDE techniques
for concrete inspections
Testing materials harvested
from reactors
Determine remaining useful
life of electrical cables
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Together…Shaping the Future of Electricity
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